He wouldn't benefit much.. He became crippled so using the CM in V1 or V2 couldn't be used as a defence as he began using Pein Rikudō no Jutsu. In addition to this, Nagato possess un-matched chakūra reserves, which easily surpass the likes of most Bijū so using the Cursed Seal wouldn't help too much in the Chakūra Providing department. It would be interesting to see, Nagato in CM V2 Mode..